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Original Investigations

Long-term Outcome of Short Metallic Stents for Lobar Airway Stenosis

Fruchter, Oren MD, FCCP*,†; Abed El Raouf, Bayya MD†,‡; Rosengarten, Dror MD†,‡; Kramer, Mordechai R. MD, FCCP†,‡

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Journal of Bronchology & Interventional Pulmonology: July 2017 - Volume 24 - Issue 3 - p 211-215
doi: 10.1097/LBR.0000000000000371
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Abstract

The primary indication for an airway stent is to reestablish patency of a major-central airway.1,2 Stenting, whether for benign or malignant disease, should be used only when all other treatment options are exhausted or contraindicated due to patient factors, such as associated irreversible comorbid conditions.2 Stents have been used to relieve central airway obstruction resulting from benign conditions, such as posttracheostomy and postintubation tracheal stenosis,3,4 stenosis of main bronchial anastomosis following lung transplantation,5–12 and malignant obstruction of major airways.13 Whereas stenting is considered an excellent solution for central airway obstruction involving the trachea and mainstem bronchi, stenting to relieve airway stenosis and obstruction of smaller airways, namely lobar bronchi, is still questionable.

Whereas the clinical and physiological benefits of relieving central airway obstruction by stent are easily comprehensible, the advantages and objective improvement in patient’s respiratory status following lobar stenting are not clear. Several authors seriously question the potential benefits of stenting nonmajor airway obstruction, regardless of underlying etiology for stenosis.14–16

In a previous report, we described the use of small airway stents to treat lobar stenosis in patients with anthracofibrosis.17 In the current report, we wish to describe our experience in treating lobar airway obstruction, resulting from benign and malignant conditions, by placement of metallic stents. We focused on both short-term success and long-term durability of the procedure and on both subjective and objective benefits for the patients. Our hypothesis was that despite the fact that only relatively small airways were treated by stents, the clinical and physiological benefits would justify such an approach in selected cases.

PATIENTS AND METHODS

We retrospectively analyzed the clinical course of all patients who underwent metallic stent placement for lobar stenosis and obstruction from July 2007 to July 2014 at the Rabin Medical Center, a tertiary-care University-affiliated medical center. Ethical approval was obtained from the Local Research Ethics Committee (#014-14) and informed assent obtained from all patients before the procedure.

Bronchoscopic Procedure

Before the decision to place a stent was made, previous techniques to manage stenosis were attempted in all patients, these included mechanical debridement, Nd:YAG Laser photoresection (SHARPLAN-3000, SHRPLAN Lasers), and Balloon dilatation (Balloon dilatation catheter; CRE; Boston Scientific Corporation, Watertown, MA). Only when residual stenosis was >75%, a decision was made to place an airway stent to maintain airway patency.

Before bronchoscopy, each patient underwent a standard preoperative assessment, including physical examination, routine laboratory tests, spirometry, chest radiography, and computed tomography (CT) scan of the chest. All bronchoscopic procedures were performed in an ambulatory day-care setting. To provide analgesia and sedation, midazolam (1 to 10 mg) and alfentanyl (0.5 to 1.5 mg) were administered. If deemed necessary, supplemental doses of propofol (20 mg) were administered at an interval of 2 to 5 minutes. The procedures were carried out with supplemental oxygen through a nasal cannula. In all procedures, bronchoscopy was performed using a large working channel bronchoscope (Olympus Excera, BF-1TQ180 II video endoscope; Olympus, Tokyo, Japan). The stents that were used: SMART nitinol stent (Laser-cut, single Nitinol tube; Cordis, Miami, FL) or PALMAZ (laser-cut stainless steel slotted tube; Johnson & Johnson, New Brunswick, NJ, and Interventional Systems, Warren, NJ). Guidewire (Zebra) was passed through the working channel of the bronchoscope and the bronchoscope was withdrawn keeping the guidewire in place. Stents were passed over the guidewire and were deployed in proper position under dual control: direct vision by keeping the bronchoscope inserted through the left nares and fluoroscopy.

Follow-up Protocol

All patients were followed every 3 months by detailed medical interview and physical examination, pulmonary function tests, and chest imaging (chest x-ray or CT scan). The patients were given aerosol inhalation with 3% NaCl 3 times a day for the first month following stent placement. Bronchoscopy was carried out every 6 months to clear secretions and remove granulation tissue growth within the stent. Unscheduled bronchoscopy was carried out when clinical deterioration was noted, namely worsening dyspnea, drop in pulmonary function tests [drop in forced expiratory volume in 1 second (FEV1) of >10%], or new significant findings on chest imaging, such as lobar atelectasis or nonresolved pneumonia.

RESULTS

Over a 7-year period, 14 patients underwent stenting of lobar airways, due to benign or malignant underlying etiologies. Patient’s demographics, procedure details, and follow-up data are provided in Table 1. Patient’s symptoms were mainly effort dyspnea, persistent cough, and recurrent nonresolved lobar pneumonia. The etiologies for airway stenosis were: early post-lung transplantation bronchial stenosis (N=5), sarcoidosis (N=1), amyloidosis (N=1), anthracofibrosis (N=1), right middle lobe syndrome due to external lymph node compression (N=1), lung cancer (N=4), and stenosis of the left upper lobe of unknown etiology (N=1). Stents were placed in the right upper lobe bronchus (N=2), right middle lobe bronchus (N=6), left upper lobe bronchus (N=4), linguar bronchus (N=1), and left lower lobe bronchus (N=1). A representative demonstration of lobar stent is presented in Figure 1 (bronchoscopic image) and Figure 2 (CT image).

TABLE 1
TABLE 1:
Demographic and Clinical Characteristics of the Study Patients
FIGURE 1
FIGURE 1:
Severe obstruction of the right middle lobe in a 70-year-old female patient (#9) with sarcoidosis resulting in recurrent pneumonia episodes following PALMAZ 6/20-mm metallic stent placement.
FIGURE 2
FIGURE 2:
Computerized tomography image of the right middle lobe stent of the same patient (#9).

All procedures were well tolerated, no immediate complications such as major bleeding or pneumothorax occurred, and all patients were discharged within 24 hours. All patients were followed for a median of 18 months (range, 2 to 72 mo). Short-term success of the procedure, defined as objective improvement in patients’ complaints, was recorded in 13/14 (92%) of patients within the first 3 months. Subjective improvement included decrease in cough intensity, improved dyspnea on exertion, and significant improvement in general quality of life. During follow-up, 3 patients with malignant etiology for lobar obstruction died from underlying disease (median time to death 24 mo; range, 2 to 35 mo). One patient who underwent left lung transplantation and stent placement in the left upper lobe died from bacteremia and sepsis 12 months following stent placement. The remaining 10 patients are alive as of the writing of this manuscript. All patients reported significant improvement in their functional capacity since the procedure, which was maintained throughout the follow-up period. Functional capacity was objectively measured by the 6-minute walking distance test that increased by a mean of 80 meters. Median improvement in FEV1 6 months following the procedure was 15.5%.

All patients needed repeated scheduled bronchoscopic procedures every 3 to 6 months to clear mucosal plugging and granulation tissue growth within the stent. Two patients required unscheduled bronchoscopy 2 and 5 months following stent placement and in both cases only purulent secretions were removed. No patient developed poststent atelectasis of the treated lobe, and only 1 patient (patient #11) developed right middle lobe postobstructive pneumonia 7 months following stent placement, due to granulation tissue within the stent that was relieved by Nd:YAG laser (that was used to photoresect granulation tissue within the stent) and mechanical dilatation of the stent by balloon.

DISCUSSION

Interventional bronchoscopy methods are useful tools to relieve central airway stenosis due to inoperable malignant tumor, or less commonly, benign conditions that may lead to respiratory distress and infection. If the obstruction is exclusively or mainly due to compression from outside the airway wall, the only option consists of placement of a stent.1,2 A variety of different stent models including the Dumon silicone stent and self-expanding metallic stents have been commercially available over the last 20 years.2 Although The FDA issued a Public Health Notification (2005)18 to alert health care professionals to serious complications associated with the use of metallic stents in patients with benign airway disorders, many interventional bronchoscopy experts believe that in carefully selected patients these stents can be used.

The subjective and objective benefits of stents in treating major-central airway obstruction (involving the trachea and mainstem bronchi) are well known, based on the physiological advantage in opening major airway obstruction. In contrast, the physiological benefits of lobar stent placement during which no central airway opening is attempted are not readily apprehensible.14,15

The major finding of the current report is that stenting of lobar airways by a metallic stent for benign conditions, in particular, nonanastomotic airway obstruction following lung transplantation, is well tolerated, and provides both immediate and long-term relief of obstructive symptoms.

Data specifically regarding the benefits of lobar stenting is sparse. Most groups to date have described their experience in treating benign and malignant conditions by stents; however, the vast majority of patients described had central airway stents.3,5,9

The current series is the first, to the best of our knowledge, which focuses exclusively on patients with lobar stents. The immediate and long-term benefits of lobar stents we observed are similar to those reported on major airway stents.

We believe that lobar stents provide objective and subjective benefits and should be considered in the following scenarios.

  • Prevention of recurrent lobar pneumonia by providing patent lobar bronchus for continuous clearing of secretions. In these carefully selected patients opening a lobar bronchus, such as the right upper or middle lobe bronchus, despite the fact that these lobes provide a small percentage of total lung gas exchange, ensures prevention of recurrent pneumonias with associated morbidity and possible mortality.
  • We believe that a stent should be considered in maintaining bronchial patency of nonanastomotic bronchial stenosis in selected group of patients who underwent lung transplantation. Two patterns of bronchial stenosis following lung transplantation have been described: the first and most common is at the surgical anastomosis site and the second, a more distal bronchial narrowing referred to as segmental nonanastomotic bronchial stenosis.7,8 Segmental nonanastomotic bronchial stenosis is rare with an estimated incidence of 2.5% to 3%.8,9 In these patients, in particular in patients following single lung transplantation, in whom the native lung is practically nonfunctional with negligible perfusion opening, a lobar bronchus in the transplanted lung is physiologically equivalent to opening a severe central airway obstruction in a patient with 2 functional lungs. Despite the fact that many centers discourage the use of metallic stents for benign conditions,2 this concept is not accepted by all.3 In fact, we have previously demonstrated that metallic stents placed in patients with lung transplantation can be easily retrieved, therefore we suggest that they should be used more liberally.17
  • The third suggested indication for lobar stenting is to provide lobar patency in lung cancer patients who had undergone lung resection, and in whom the patency of the remaining lung tissue is mandatory for acceptable quality of life. In these patients, life expectancy should be carefully weighed against symptoms relief by stenting, and we suggest that airway stenting should be reserved for a selected subgroup of patients with malignant lobar obstruction. The best regimen of follow-up after stent placement remains to be determined, but although long-term complication rate is low, surveillance bronchoscopic procedures should be considered every 6 to 12 months to maintain and ensure stent patency.

The major limitation is that our conclusions are based on a retrospective set of data on a small series of patients. More prospective large-scale studies are required before lobar stenting becomes standard of care in routine practice.

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Keywords:

bronchoscopy; lung cancer; lung transplantation; stent

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